Multicolor photographic elements containing various yellow image dye-forming couplers in a blue light sensitive layer are known. Typically, such couplers are based on open chain keto-methylene compounds, usually either alkyl- or aryl-acyl acetanilides. Couplers that form yellow dyes upon reaction with oxidized color developing agent are described in such representative patents and publications as: U.S. Pat. Nos. 2,298,443, 2,407,210, 2,875,057, 3,048,194, 3,265,506, 3,447,928, 4,022,620, 4,443,536, and "Farbkuppler-eine LiteratureUbersicht," published in Agfa Mitteilungen, Band III, pp. 112-126 (1961). These known couplers include those employing a heterocyclic coupling-off group such as one based on a hydantoin moiety.
Yellow image dye-forming couplers have been used with various groups bonded at the coupling site. The portion of the coupler which couples with oxidized developer is usually referred to as the "parent" or "Coup" group. The term "image dye-forming" coupler generally means a coupler that has as its principal function the function of providing image dye density. Such couplers may be distinguished, for example, from masking couplers which have as a primary purpose masking unwanted absorptions through providing one color in exposed areas and another color in unexposed areas and may be distinguished from "PUG" releasing couplers which have the primary function of releasing PUGs (Photographically Useful Groups) which improve sharpness etc.
For image dye-forming couplers, the parent or Coup group may be bonded at the coupling site to hydrogen or, more commonly, to a "coupling-off" (COG) or "leaving" group. The use of leaving groups rather than hydrogen is generally preferred for various reasons, foremost of which is that they provide more efficient dye formation relative to silver development. Coupling-off groups of the art generally include a wide variety of chemical groups including both aryloxy and heterocyclic groups, and these are discussed in more detail in the patents identified in the first paragraph of this section. None of these coupling-off groups have been altogether satisfactory.
Yellow dye-forming couplers containing an aryloxy coupling-off group have been deficient in photographic properties, particularly from the standpoint of raw stock keeping. It has been observed that the presence of such couplers containing an aryloxy coupling-off group fosters degradation of the film upon storage prior to exposure. This results in loss of image dye density and the formation of undesirable by-products as a function of time. Since it is desired that an identical image of an object be obtained regardless of raw stock storage time, this degradation needs to be minimized.
On the other hand, the use of heterocyclic coupling-off groups has lead to color reproduction problems. The hue of a dye produced by an image dye-forming coupler is dependent on the formula of the parent portion of the parent/coupling-off group compound and on the identity of the coupling-off group. The coupling-off group, once replaced by oxidized developer, remains in the vicinity of the reaction and influences the hue of the dye formed. In the particular case of heterocyclic coupling-off groups, the hue of orange and blue objects has proven to often be unsatisfactory when these types of couplers are employed.
U.S. Pat. No. 4,273,861 suggests the use of interlayer color correction couplers to improve color reproduction. Various suggestions are made for the inclusion of development inhibitor releasing couplers in particular layers to improve color reproduction. No suggestion is made of the hue problem occasioned by the use of t-butylacylacetanilide yellow couplers having a heterocyclic coupling-off group in the blue sensitive layer nor is there any suggestion to include a magenta image dye-forming coupler in a blue sensitive layer.
According to the abstract of Japanese published patent application 05/072,690, it has been suggested to employ magenta or cyan couplers in the blue sensitive layer of a photographic element in combination with one of three yellow dye-forming couplers which are either diamides or which have a ring adjacent the acyl carbon for the purpose of improved dye stability and increased maximum dye density. The abstract does not suggest photographic elements having a blue sensitive layer containing a t-butylacylacetanilide yellow image dye-forming coupler nor does it suggest that improved raw stock keeping and color reproduction are obtainable.
There is therefore a need for a photographic element which provides the combination of good raw stock keeping characteristics while also providing good color reproduction.